When an extra-terrestrial visitor arrives on Earth, his first impressions of the human species are less than positive. Taking the form of Professor Andrew Martin, a prominent mathematician at Cambridge University, the visitor is eager to complete the gruesome task assigned him and hurry home to his own utopian planet, where everyone is omniscient and immortal.

He is disgusted by the way humans look, what they eat, their capacity for murder and war, and is equally baffled by the concepts of love and family. But as time goes on, he starts to realize there may be more to this strange species than he had thought. Disguised as Martin, he drinks wine, reads poetry, develops an ear for rock music, and a taste for peanut butter. Slowly, unexpectedly, he forges bonds with Martin’s family. He begins to see hope and beauty in the humans’ imperfection, and begins to question the very mission that brought him there.